The embodiments relate to an apparatus and a method for the detection of liquids or substances from liquids in spatially different reaction regions. A corresponding apparatus and a method for the operation thereof are disclosed in DE 10058394 C1. The embodiments furthermore relate to the use thereof in a smart card which can be used with the aid of a read-out device for e.g. immunological fast tests. In this case, the liquids or substances from liquids are detected by means of a sensor array which is composed of at least two sensors and on which at least one membrane is arranged.
In biochemical analysis technology, sensor arrays having e.g. electrochemical or optical sensors are increasingly being used in order to test the composition of liquids such as e.g. blood or urine for specific substances rapidly and cost-effectively. Thus, DNA analyses can be performed by means of sensor arrays having sensors which are coated with different DNA catcher molecules. Urine samples from subjects can be examined for pathogens by virtue of the fact that, in sensor arrays, sensors are coated with antibodies and the specific binding of the pathogens to the corresponding antibodies is measured. In this case, one preferred measuring method is the electrochemical measurement of substance conversion that only occurs on specifically bound molecules.
In order to attain good handling of the sensor arrays, recent developments are aimed at integrating the sensor arrays into small, compact, portable systems such as smart cards, for example. The latter contain a chip with a sensor array integrated thereon, microfluidic channels for liquid transport to and away from the chip, reaction chambers for reactions such as e.g. disintegration of blood and subsequent polymerase chain reaction (PCR), and also chambers containing chemical reagents preferably in dry form. Standardized smart cards are constructed from plastic and can be introduced into analysis devices in a simple manner. Beforehand, the liquid to be examined that is taken from the patient is applied onto or introduced into the smart card, the dry reagents are dissolved and reactions necessary for the detection are initiated. When the smart card is introduced into the analysis device, the sensors on the chip are activated by the analysis device via electrical contacts on the smart card and can, under closed-loop or open-loop control, measure biochemical reactions and also output the results of the measurement to the analysis device in the form of optical or electrical signals. The result can then be output by the analysis device, after evaluation by a computer-aided unit, via a monitor or other indicator instruments.
In order to attain an increased measurement accuracy and a lower error rate during the measurement, the prior art, such as e.g. DE 10058394C1, discloses a method and an associated arrangement wherein the sensors of the sensor array are separated from one another during the measurement in such a way that no liquid can flow from one sensor to the other. The sensors of the sensor array are arranged on a planar surface with walls between the individual sensors, wherein the walls project from the surface. A housing upper part is arranged parallel to the planar surface of the sensor array at a distance from the walls, the housing upper part being at a sufficient distance from the surface and the walls to allow liquid to flow between the surface and the housing upper part. Before the measurement, the housing upper part is pressed in the direction of the surface with walls with the aid of a plunger, such that the walls and the housing upper part are in close contact.
The flowing of the liquid has been prevented, and closed-off reaction spaces, delimited by the planar surface, the walls and the housing upper part, have been produced above the sensors. The liquid which has been enclosed in the reaction spaces can then be examined without exchange of liquid between different reaction spaces. The measurement of the sensors takes place with the aid of the closed-off reaction spaces independently of one another.
The method described in the prior art in accordance with DE 10058394C1, for example, leads to a complicated arrangement with housing upper part and plunger wherein the walls between the sensors have to correspond to precise dimensions. These precise dimensions are difficult to realize in practice:
If the walls project too little from the planar surface in which the sensors are arranged, then this gives rise to reaction spaces which are too small and have an amount of liquid that is too small to carry out a meaningful measurement. The housing upper part can, under certain circumstances, be seated on the sensors at high plunger pressure, whereby the measurement is corrupted.
If the dimensions of the walls are made too large, then the sensors have to be arranged at a larger distance from one another, and the required amount of liquid for filling the arrangement increases. This means that the sensitivity of the measurement turns out to be lower and the number of sensors available for measurement decreases for the same area since the dimensions of the sensors have to be made larger in order to achieve a sufficient measurement accuracy.